Autoren: Torres, Nadeau, Landau
Kategorie: Gesundheitsschutz und Arbeitssicherheit
General fatigue has for decades been a subject of research in safety-critical domains like aviation or process industry, due to its negative effect on performance and the potentially catastrophic accidents’ outcome. High levels of general fatigue in manual assembly can induce error-related quality issues and generate economic losses. In manufacturing, variations in production levels due to different factors, make overtime a necessary practice as is the case in the present study. Two assembly lines were considered where 66 assemblers were assigned at the time of the study. The assemblers rotate between two shifts: morning shift (6h60-14h30) and evening shift (14h30-00h30) doing three morning shift weeks and one evening shift week alternatively. Overtime is allocated adding 4h blocks to shifts or by adding working days to the workweek. The evaluation of potential levels of fatigue associated to these practices was conducted using the HSE Fatigue Index developed by the Health and Safety Executive (HSE) in the United Kingdom. In total, eleven different shift arrangements or scenarios (six morning workweeks and five evening workweeks) were evaluated. Scenarios were built with the collaboration of supervisors and based on data from the work hours system. Data shows that overtime can, in some cases, be significantly higher than a normal workweek of 40h (80% more). In general, all morning scenarios had smaller values of FI than evening scenarios. In morning scenarios, there is little difference on FI whether the workweek is extended (2 more workdays) while keeping shift length unaffected versus the workweek is kept the same (5 workdays) but adding 4h blocks after the shift (16.9 vs. 15.4). This was not the case for the evening shift were these two different strategies had a major difference on the impact on FI (14.3 vs. 34.1). Overtime allocation strategies should consider the effect on fatigue depending on the type of shift. It is preferable for the morning shift to extend the length adding 4h blocks while for the evening shift is preferable to extend the workweek. Supervisors should consider these results in the working time management practices.
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Torres, Nadeau, Landau